1. Field
Aspects of one or more embodiments of the present invention are directed toward data communication using an existing radar aperture, and, in particular, pulsed data communication between radar platforms.
2. Description of Related Art
A radar system uses electromagnetic waves to identify fixed or moving objects such as aircrafts, ships, motor vehicles, and terrain, etc. A typical radar system has a transmitter that emits a radio wave that is partly reflected back by an object, and the reflected signal has a slight change of wavelength (or frequency) if the target is moving. The radar system also has a receiver for receiving the reflected signal. The transmitter and receiver may be located at the same physical location or different locations. The radar system may include one or more transmitters and/or one or more receivers.
A multiple input multiple output (MIMO) radar system includes a plurality of transmitters for transmitting RF signals to illuminate one or more targets and a plurality of receivers for receiving backscattered RF signals from the one or more targets. In the MIMO radar system, the transmitters and receivers may be located on a plurality of platforms physically distanced from each other. Each of the platforms may include one or more transmitters and/or one or more receivers, and the platforms may be stationary (e.g., a ground based radar station) or mobile (e.g., an aircraft or motor vehicle). In addition to performing radar sensing functions, the transmitters and receivers of the MIMO radar system can be utilized for providing a high-speed data link among the platforms constituting the MIMO radar system. That is, using the radar's antennas (or apertures) concurrently for radar sensing and transmitting/receiving high-speed data, a large amount of data (e.g., radar sensing data) may be shared among the platforms. In a MIMO radar system that performs sensing in pulsed mode, communication data may be sent between radar scans as pulsed communication signals such as Radar Common Data Link (R-CDL) or Pulsed Common Data Link (P-CDL) waveforms. In addition, each platform includes a suitable modem for converting (e.g., modulating) digital communication data to analog signals to be transmitted by its antenna or converting (e.g., demodulating) analog signals received from its antenna to digital communication data. Therefore, it is desirable that the modem can handle P-CDL waveforms. While commercial-off-the-shelf (COTS) or off-the-shelf (OTS) modems are widely available, such modems are typically not capable of modulating/demodulating R-CDL or P-CDL waveforms directly. It is known that an R-CDL modem has been developed by L3 Communications Corporation to handle P-CDL waveforms by employing coherent demodulation using preamble/postamble detection. It is desirable to provide a solution to utilize standard COTS or OTS moderns to handle P-CDL waveforms.